heck of a deal on a full AR there.
I got that upper when PSA had the upper sale, I’m happy with it.
I am partial to the mid and rifle length gas system and have a 16" mid and a 20" rifle length AR.
Not quite as loud, slower cycling thus less wear and tear on bolt and upper receiver. Added bonus of higher muzzle velocity due to gas pressure behind projectile for a longer period before gas block.
That’s just me, old school and not very adventurous when it comes to guns. 
I’m frozen in a traditional gun time matrix - and if I had a time machine would go back rather than forward even if upset the space time continuum